M. Heydari-Malayeri - Paris Observatory

A → photometric system defined by reference to
→ monochromatic magnitudes in such a way that, when monochromatic
→ fluxfν is measured in
ergs sec-1 cm-2 Hz-1,
the magnitude will be:
AB = -2.5 logfν - 48.60.
The constant is set so that AB is equal to the V magnitude
for a source with a flat → spectral energy distribution.
The → zero point is defined by the flux of the star
→ Vega at 5546 Å.
In this system, an object with constant flux per unit frequency interval has zero color.